Chemistry Reference
In-Depth Information
under the trade name of Biopol, is available commercially with a range of properties, such as melting
point, toughness, flexibility, and others. The melting points range from 80 to 180
C.
It was reported that
microorganism can be forced to produce a thermo-
plastic elastomer by growing it on a substrate containing sodium octanoate [
71
]. The product is poly
(
Pseudomonas oleovorans
-hydroxy octanoate). It contains crystalline regions that act as physical cross-links.
Also, addition of poly(ethylene glycol) of molecular weight 200 to cultivation media of
Alcaligines eutrophus
b
during polymer formation, where the carbon source used is 4-hydroxybutyrate,
affects the type of ester that it produces [
73
]. Addition of this glycol in amounts from 0 to 2% by
weight results in increased amounts of 4-hydroxybutyrate incorporation from 66 to 86 mol.% into the
produce, poly(3-dydroxyalkanoate). When, however, the amount of the glycol is increased to 4%, the
amount of incorporation of the 4-hydroxybutyrate decreases to 64%. The product then also contains a
diblock copolymer of poly(3-hydroxyalkanoate) and poly(ethylene glycol) [
73
].
Review Questions
Section 8.1
1. List the six main categories of naturally occurring polymers.
2. Draw the chemical structures of the repeat units of each category of naturally occurring polymers.
Section 8.2
1. Describe hemicellulose. This should include an explanation of what xylan, galactan, araban, and
plant gums.
2. In discussing starches, explain what are amylose and amylopectin. Explain and draw structures.
3. Discuss cellulose. How does cellulose differ from starch?
4. What is cellobiose? Draw the structure and give the chemical name.
5. What is regenerated cellulose? Explain what is Chardonnet silk, Cuprammonium rayon, and
viscose rayon and how they are prepared.
6. Discuss the chemistry of cellulose nitrates. How are they prepared and used?
7. Discuss the chemistry of cellulose acetate. How is it prepared and used? Describe mixed cellulose
esters.
8. Discuss the chemistry of cellulose ethers.
9. Show the reaction of cellulose with acrylonitrile.
10. Iodocellulose can be dehydrohalogenated to form double bonds in the polymer. This can be used
to form new derivatives. Give two examples.
11. Draw the structures of alginic acid and chitin.
Section 8.3
1. Discuss the chemistry of lignin, drawing the structure of coniferyl alcohol. Can you think of a
useful product from lignin?
